The “Field of the Invention” and “Description of the Prior Art” sections have been combined under a single section.
The present invention relates to a joystick device for use as an operation device in operating construction equipment such as a hydraulic excavator or a crane.
Heretofore, joystick devices have been widely used to control various actuators (including a hydraulic cylinder, a motor and the like) included in construction equipment such as a hydraulic excavator or a crane.
FIG. 8 is a side elevational view of such a conventional hydraulic excavator, while FIG. 9 is a side elevational view of the interior of a control cabin of the conventional hydraulic excavator. As shown in FIG. 8, the hydraulic excavator includes a bucket 102, an arm 103, a boom 104, and like parts. The operator of the hydraulic excavator vertically or laterally tilts a operate lever 202 of a joystick device 201 disposed at a suitable position in the control cabin to control the operations of actuators. Thus, it is possible to control operations of the excavator including, for example, excavation/dumping with the bucket 102, raising/lowering of the arm 103 and boom 104, and turning to the right or left of the main body of the excavator.
The joystick device 201 has a grip portion provided with at least one operation button 203 on a surface thereof. The operator is capable of turning ON/OFF a switch incorporated in the joystick device 201 by depressing the operation button 203. By so doing, it is possible to control operations of the excavator including expansion/contraction of a hydraulic cylinder, forward and backward revolution of a motor, or like operations. The hydraulic cylinder and the motor function as an actuator for attachments (including a crusher and a grapple for example) of the bucket 102.
Usually, two such operation buttons 203 are provided as one set and each of the buttons 203 correspond to one such switch as described above. The switch corresponding to each operation button 203 is turned ON/OFF alternately to achieve switching between expansion and contraction of the hydraulic cylinder or between forward revolution and backward revolution of the motor.
Such a conventional joystick device 201 has a function of outputting a hydraulic or electric signal proportional to the amount of operation of the operation lever 202 when the operation lever 202 is tilted. Thus, the joystick device 201 is imparted with such high operability as to control expansion/contraction of the hydraulic cylinder, revolution of the motor or like operations at a speed proportional to the angle of tilt of the operation lever 202. As a result, the joystick 201 is capable of easily performing fine controls in positioning of the bucket 102 for example.
On the other hand, the aforementioned attachments are controlled based on ON/OFF switching through depressing of the corresponding operation buttons 203 and, hence, expansion/contraction of the hydraulic cylinder or the revolution of the motor can be controlled not at a variable speed but at a constant speed. The hydraulic cylinder and the motor function as the actuator of such an attachment. For this reason, the joystick device 201 has a difficulty in fine controls of the attachments such as positioning.
Further, in some cases the disposition of the two operation buttons 203 of the conventional joystick device 201 does not correspond to the direction in which the corresponding attachment is to be displaced, thus resulting in poor operability. Specifically, if an attachment adapted to rotate laterally is controlled with two operation buttons 203 that are vertically arranged in a row for example, the disposition (vertical direction) of the two operation buttons 203 does not correspond to the direction (lateral direction) in which the attachment is to be displaced, which raises a problem that the operator, particularly one who is unfamiliar with the operation of such a joystick, must pay attention to the difference in direction every time the attachment is to be operated, or like problems.
The present invention has been made in view of the foregoing circumstances. It is, therefore, an object of the present invention to provide a joystick device imparted with improved operability as compared with the prior art by virtue of the provision of operation means enabling proportional control at the tip of an operation lever or the provision of operation means of which the disposition is changeable in accordance with the direction in which a subject for operation is to be displaced.